Alrighty, the job is done and I would like to share some thing I learned:
-It doesn't matter how tired and Done they are, the vast majority of people will react positively if you approach them with a smile and shamelessly express admiration for something important to them (in this case, the dog)
-They are also extremely willing to talk at length if you so much as shoot them a wide-eyed interested look.
-Some people really have reached their limit for the day and they won't react well to you no matter how you approach them. You really, REALLY have to internalize the fact that it's not about you, they have just hit their people limit for the day, and you have to shrug it off and move on.
-People love free stuff. They love it even more if you act like you're breaking some minor rule to give them free stuff.
-Networking really does come down to you knowing people who know people and say you're willing to put them in contact with each other. Even if you hedge your bets and prevaricate by saying 'I'd have to ask' people are willing to take the chance and give you all kinds of stuff to sweeten the deal. I came home with three giant bags and two even bigger boxes of free samples of dog and cat food, a lecture for my mom to attend and a supply deal for mom's charities. And possibly a vet partnership for my emoloyer.
-Bringing a thermos of coffee to work makes people look at you like you're a literal godsend. Bringing a bottle of alcohol for the last day makes you the best neighbor.
-Some people get a little nervous with eye contact. It helps if you're looking at the dog when talking to them. Or if you do have to talk to them about paperwork and stuff, if you wear a funny hair ornament (in my case a hairpin with a dangly silk orchid) they will talk to the hair ornament half the time but the conversation will be much smoother.
-The stall owners are usually wary about handing out their free samples too generously and running out before the end of the event. But on the last day they face the dilemma of hauling all that stuff home, so they will pack you an entire bag of free stuff and hand it over with a smile just so they don't have to pack it up. Bonus point if you exchange it for some of your free stuff. And if you're just a convention-goer and not a stall-owner the same principle applies, and the guards aren't paid enough to keep you away on the last day. "I'm just here to help pack up" are the magic words.
In conclusion: Friendliness and a touch of shamelessness gets you friends and free stuff. You wouldn't believe how easy humans are to hack.